The overall goal of this project, Cumulative Environmental Effects: Expanding Research with the Hopi Tribe, is to use a community-based participatory research (CBPR) approach to collaborate with the Hopi Tribe investigating household exposures to inform policy decisions. Household exposures are major sources of environmental hazards encountered by many American Indian and Alaska Native (AI/AN) communities. Household exposures include combustion by-products from heating and cooking, particulate from nearby mining and other land uses, and water and food contamination. These exposures, and co-exposures such as unemployment and poor access to preventive programs and health services, impact respiratory health and obesity among children and adults, and warrant evaluation of AI/AN household exposures within a social ecological framework. The Hopi Tribe in northern Arizona has identified several areas of concern, including the impact of burning coal and biomass in homes for heating and its potential impact on respiratory health. Other issues include concerns about arsenic and uranium species in drinking and surface water. Arsenic exposure is linked to compromised lung function and an increase in body mass index. This application seeks to expand existing relationships to include Hopi officials in the Hopi Environmental Protection Office and university environmental scientists and health promotion experts. The project proposes to: 1) Characterize magnitude of environmental exposures to particulate matter (PM), arsenic species, uranium and other contaminants from air, water, and food in selected households on Hopi tribal lands; 2) Evaluate how exposures are moderated by social determinants of health, social capital, community resilience and other cultural assets; and 3) Expand Hopi capacity to address areas of environmental concern. The effort will build additional capacity within the Hopi Tribe to evaluate and mitigate environmental hazards of concern to the Tribe. The proposed joint project provides an opportunity to develop and strengthen a relationship built on trust between the Hopi Tribe and university researchers and to increase the capacity of the Hopi Environmental Protection Office to monitor its air and water quality. Anticipated results include modeling of cumulative exposures to arsenic species and particulate among Hopi residents and addressing environmental concerns of the Tribe in terms of health inequities. The project will build the Hopi Tribe's capacity to conduct research on adverse exposures and develop programs that inform tribal environmental and health policies for a sustainable future.